The present invention relates to keyboard-video-mouse (KVM) switches with virtual media support.
KVM systems include a switch unit (also called a Smart Switch) and peripheral units (referred to herein as a “ROC”, also called a “dongle”). Peripheral units are connected to one or more computers (e.g. servers) that are to be remotely controlled (see FIG. 1). The ROC unit includes serial connectors to couple to the server's keyboard and mouse (e.g. using standard serial connection formats such as USB or PS/2) as well as to the server's video output (e.g. a VGA connection), which is generally an analog component video RGB output.
The communication between the Smart Switch and each of the ROCs is carried over a cable, typically a CAT5 cable (although other types such as CAT6 or CAT7 are possible; for clarity this discussion will use the term “CAT5” to include all such possible cable types), which connects at one end to the KVM switch and at the other end to the ROC. The CAT5 cable contains four twisted pairs of wires. Currently, the analog RGB video along with vertical and horizontal sync pulses are transferred over three of the pairs and the fourth pair is used to implement a half-duplex serial RS485 data communication between the ROC and the switch (FIG. 2). In half-duplex communication mode, each of the ROC and the switch, after a short predetermined time after finishing the transmission, changes automatically to a receive mode. In current implementations of virtual media, data transfer rates are limited to RS485 supported rates in each direction.
While the data transfer rate of this serial communication protocol is sufficient for transmitting signals relating to keyboard and mouse operation, it is relatively slow when it comes to transmitting data files, for example when accessing virtual media. Remote virtual media is a method of connecting a remote media source (i.e. CD-ROM drive, hard disk drive, floppy disk drive, or virtual implementation of any of them) to a local system. The local system can access the remote (and possibly virtual) media and can potentially read from and write to that media as if it were physical and local. Examples of remote media include a physical disk drive of any type available remotely to a local computer.
Remote virtual media is a useful tool for those who manage large numbers of computers, such as commercial IT data center managers. A local computer can boot to one of many virtual disks that can perform any variety of tasks, such as virus scans of the local physical drive and patch management, or even complete installation of the local operating system.
However, a faster data transfer rate is needed between the KVM switch and the ROC in order to provide adequate support for the amount of data users wish to transfer.